The EU is more than halfway to its target of cutting emissions by 20% from 1990 levels by 2020, a report shows.

The assessment by the European Environment Agency (EEA) reveals that emissions across the 27-nation bloc fell to 11.3% during 2008.

However, the EEA adds that the global economic downturn played a key role in the reduction.

Campaigners are calling on the EU to set more ambitious targets in order to tackle climate change.

"The greenhouse gas inventory shows that the EU is well on track to meet its emission reduction targets," said EEA executive director Professor Jacqueline McGlade.

"Although we are expecting an even sharper decline in 2009, caused mainly by the recession, we need to ensure that the downward trend in emissions continues and that Europe boosts its climate investments."

The assessment also showed that emissions from international aviation and maritime transport fell for the first time since 1992.

The EEA report added that the decline in these sectors was partly a result of the economic slowdown.

However, it showed that households in Europe saw their emissions rise, primarily for heating purposes because of lower temperatures during 2008 than in the previous year.

Overall, total emissions in the 27-nation bloc have been falling since 2003.

Downturn in demand

Data shows that greenhouse gas emissions fell by 99 million tonnes of carbon dioxide equivalent (CO2e) during 2008, making a total net reduction of 627m tonnes of CO2e from 1990 levels.

A huge slice of the 11.3% reduction was achieved long before the EU's Emissions Trading Scheme got underwayDamien Morris, Sandbag

The 15 nations that made up the EU before it expanded to 27 countries are obliged under the Kyoto Protocol to reduce emissions by 8% between 2008-2012 from 1990 levels.

They also saw their emissions fall during 2008.

The countries - which include the UK, France, Spain and Germany - recorded a 76m-tonne CO2e reduction, taking emissions to 6.9% below 1990 levels.

The EEA report identified a range of factors that contributed to the reduction during 2008, including less demand for power as economic activity slowed.

The agency also suggested that high coal prices combined with a drop in natural gas prices saw nations replace coal with less polluting gas-powered electricity generation.

The apparent progress towards reaching the 2020 target has led to some campaigners calling for EU nations to adopt much more ambitious targets.

Europe's new Climate Action Commissioner Connie Hedegaard recently published a paper that set out the arguments why the EU should commit itself to a unilateral cut of 30% by 2020.

Currently, EU policy is to adopt the 30% goal only if other major emitters, such as the US and Japan, agree to make similar reductions.

A number of countries, including France and Germany, are reportedly unwilling to support a unilateral EU move to 30%.

Damien Morris from Sandbag, a carbon trading campaign group, said he was supportive of the push for the higher target.

"But like a lot of NGOs across Europe, we would be much happier to see 40% targets under discussion," he told BBC News.

However, he quickly added that in an effort to prevent dangerous climate change, target-based policies were "scientifically incoherent".

"The problem is the amount of CO2 entering the atmosphere along the way to any target," he explained.

He added that a number of campaigners were calling on policymakers and politicians to switch from a target-based policy to schemes that focused on carbon budgets.

Writing in the Journal Nature in April, researchers said pledges made at December's UN summit in Copenhagen are unlikely to keep the rise in the global mean temperature to 2C (3.6F) above pre-industrial levels.

Analysts at the Potsdam Institute for Climate Impacts Research in Germany said a rise of at least 3C (5.4F) by 2100 was likely.

The team added that many countries, including EU members and China, had pledged slower carbon curbs than they had been achieving anyway.

Mr Morris said the latest figures outlined in the EEA report were "fairly unimpressive".

"A huge slice of the 11.3% reduction was achieved long before the EU's Emissions Trading Scheme (ETS) got underway," he told BBC News.

The ETS is the EU's main mechanism to reduce emissions. Under the scheme, which was established in 2005, permits for emitting CO2 are distributed under a system of national allocations.

The permits can be traded among large energy users, allowing big polluters to buy extra ones from greener enterprises.

Mr Morris observed: "In fact, much of the reduction was made even before the Kyoto Protocol was ratified."

He said said that improvements in energy efficiency were driven by financial reasons, not environmental policies.

For example, he said, companies were keen to reduce their expenditure on rising energy costs in order to protect profit margins.

Business representative bodies called for a cautious approach towards increasing the EU's emissions target to 30% without other big polluting nations taking similar action.

Responding to Ms Hedegaard's paper, Dr Neil Bentley, CBI director for business environment, said: "More work needs to be done on the potential impact that raising the target would have on different sectors and on UK energy security.

"In the absence of a globally-binding climate deal, talk of unilaterally raising the EU 2020 target is premature.

"We believe a unilateral move by the EU could disadvantage manufacturers by subjecting them to higher costs than their international competitors."